Thermostatic controller for waterbed heater

Abstract

A thermostatic controller for a waterbed heater of the type where the water bladder is enclosed in a foam casing with the controller disposed between the bladder and the side of the casing. The controller has a liquid filled bulb and capillary temperature sensor disposed in a sensing chamber isolated by dead air from a separate walled switching chamber having a diaphragm type actuator connected to the capillary tube for moving a lever spring biased against the actuator and operable to actuate a snap switch. An adjustment camshaft extends externally of the controller housing for adjusting the bias on the lever for changing the temperature at which the snap switch is actuated.

I claim: 
     
       1. A temperature controller for a waterbed heater comprising: (a) housing means formed of electrically insulative material, said housing means having oppositely disposed spaced generally parallel sides and adapted for mounting on the waterbed with said sides disposed generally vertically, said housing means including wall means defining: (i) a switching chamber;   (ii) a sensing chamber;     (b) temperature sensing means comprising a liquid filled bulb disposed in said sensing chamber, with dead air space intermediate said sensing means and said switching chamber;   (c) switch means disposed in said switching chamber adapted for connection to a heater, and operable upon actuation and deactuation to make and break an electrical circuit connection;   (d) fluid pressure actuator means disposed in said switching chamber and including capillary means, connected to said temperature sensing means, said actuator means operable in response to a preselected sensed temperature to effect actuation of said switching means.   
     
     
       2. The controller defined in claim 1, wherein said housing means comprises a pair of half-shells each defining one of said sides, said shells joined about a parting line generally parallel to said sides. 
     
     
       3. The controller defined in claim 1, wherein said housing means comprises a pair of half-shells formed of non-metallic material and joined by non-metallic weldment. 
     
     
       4. The controller defined in claim 1, wherein said housing means comprises a pair of symmetric half-shells each defining portions of said chambers. 
     
     
       5. The controller defined in claim 1, wherein said switch means includes a subassembly comprising a switch mounting plate having a pair of contact means mounted thereon, said mounting plate being secured to said housing means in said switching chamber. 
     
     
       6. The controller defined in claim 1, wherein said housing means comprises a pair of half-shells joined along a parting line generally parallel to said sides; and, said switch means includes a pair of blade members mounted on one of said half-shells.   
     
     
       7. The controller defined in claim 1, wherein said switch means includes a snap-acting mechanism for opening and closing a pair of contacts. 
     
     
       8. The controller defined in claim 1, further comprising adjustment means, including a movable member accessible exteriorly of said housing movable for adjusting the actuation temperature of said controller. 
     
     
       9. The controller defined in claim 1, wherein said switch means includes (a) a lever mounted for pivotal movement in said switching chamber and operatively connected to said fluid pressure actuator; (b) adjustment means, user accessible, exteriorly of said housing means, for varying the bias of said lever means with respect to said actuator means for calibration of said controller. 
     
     
       10. The controller defined in claim 1, wherein said switch means is adjustable and includes a rotatable member extending exteriorly of said housing means, said member disposed on the top of said controller when same is mounted with said switching chamber vertically above said sensing chamber.